Stable Drivers Download
Mount the ISO inside the Windows guest. Using device manager - update drivers by pointing to
the mounted ISO. Make sure to configure the machine to use Virtio first, if it makes sense.

A note about VirtIO
VirtIO drivers are paravirtualized drivers that acts as an abstraction layer over devices in KVM guests.
Para-virtualization means the guest is partially aware of being a guest, and can send IO requests more
efficiently to KVM as a hypervisor by working together with it. Fully virtualized VMs do not know they
are being virtualized, causing more work for the hypervisor as it has to "trap" IO requests to hardware.
A fully virtualized VM will have an emulation layer close to hardware level in its hypervisor, which is
efficient, but highly complicated and less direct than a para-virtualized one.